As Colorado struggles with long-term water needs, an upcoming decision by the U.S. Supreme Court on whether to grant an appeal to a 10th Circuit ruling could vastly complicate the state’s planning and future growth.

The issue at stake is water allocation among states.

The water of virtually all the West’s major rivers, including those that flow from and through Colorado, is allocated according to interstate agreements called compacts. A total of 26 compacts have been agreed upon among states, ratified by the negotiating legislatures and enacted into federal law. Dating back in some cases to the 1920s, they have provided the essential legal infrastructure to the growth of the West since the end of World War II. The distribution of water laid out in them has always been considered legally binding — until now.

Last September, in a case involving Texas and Oklahoma (Tarrant Regional Water District vs. Herrmann), the 10th Circuit reread language in the Red River Compact — an agreement between Arkansas, Louisiana, Oklahoma and Texas — to mean that water sharing among the signatories was voluntary, not mandatory, begging the question: Why did the states negotiate the complex agreement at all?

The decision turned on a provision that is common to many of the nation’s interstate water compacts, including the Colorado and the Upper Colorado compacts: When one state gives another the right to tap its water, it doesn’t give up the right to enforce state laws on the waterway, or to impose its environmental standards, or anything else — other than the water itself.

This kind of “we mean what we say and nothing more” language is in almost every major contract ever written. But, amazingly, the 10th Circuit’s three-judge panel read it to say that Oklahoma did not have to allow Texas the water guaranteed to it at all.

No act of legal revisionism by any court in the country has so much potential to generate economic disruption. If the Supreme Court declines to review, the ruling will become law in the 10th Circuit, covering Wyoming, Colorado, Utah, Kansas, New Mexico and Oklahoma.

Through these states flow such essential rivers as the Colorado (on which metro areas from Denver to Salt Lake City to Phoenix to Southern California depend) and the Yellowstone (a major source of water for southeastern Montana and the fracking fields in that state and, after it merges with the Missouri, North Dakota). Even the Republic and Arkansas rivers, from which, ironically, northern and much of western Oklahoma receive water, come under the ruling.

Already, Wyoming has expressed opposition to the controversial Flaming Gorge Project’s diversion of allocated water to Colorado, despite the Upper Colorado River Compact’s promises. Throughout the West, the vulnerable include all states that, like Colorado, have regions dependent on compacted water from out of state.

In short, if the Supreme Court decides not to hear this case, virtually every Western state will have no choice but to engage in what could easily become as many as two dozen massively contentious negotiations on which will turn the futures of numerous metro areas and other communities, as well as industries, agricultural regions and Indian tribes. In our factious contemporary political life, can such far-reaching interstate agreements as our water compacts, arrived at in the more placid periods, be put back together, if the courts pull them apart?

In April, the high court asked U.S. Solicitor General Donald B. Verrilli Jr. whether it should take the case. His brief is expected in the fall or winter. The justices’ ruling will come not long after that.

On small hinges, great doors swing. On this hinge will swing a vast future, for Colorado, the American West and, ultimately, the entire country.

James M. Oliver is general manager of the Tarrant Regional Water District in Texas, a party in this suit.